Bone Anchored Hearing Implant Surgery: 1 Year Follow-Up Data Shows No Effect of Hydroxyapatite Coating on Soft Tissue Reaction after Loading at 1 Week

OBJECTIVE: To assess postoperative skin complications around a bone anchored hearing implant (BAHI) abutment coated with hydroxyapatite and loaded after 1 week.

DESIGN: Single center, prospective cohort study of 25 adults with expected normal skin and bone quality.

INTERVENTION: Implantation of the Baha BA400 hydroxyapatite coated implant system using a linear incision technique without soft tissue reduction. Abutments with lengths of 8 mm (n = 9), 10 mm (n = 11), and 12 mm (n = 5) were used. The implants were loaded after 7 days (n = 23), 8 days (n = 1), and 12 days (n = 1).

MAIN OUTCOME MEASURES: Soft tissue evaluation (Holger's score, skin overgrowth, pain, numbness) at 7 (±2), 14 (±3), and 30 (±7) days and 3 months (±14 days), 6 months (±14 days), and 12 months (±30 days). The results were compared with a historic control group.

RESULTS: Twenty five patients were included, 23 could be followed up for 1 year. In 93.8% of the visits, patients had a Holger's score less than or equal to 1. One patient needed revision surgery due to skin overgrowth. 18.8% of the patients experienced mild pain during follow-up, primarily during the first month. Sensibility loss was very limited. Compared with similar patients having the smooth titanium abutment (loaded at 2 wk), there was a slightly increased level of short-term soft tissue reaction.

CONCLUSION: The study shows a small, non-detrimental, negative effect on short-term soft tissue status after loading of the implant at 7 days. No positive effect from the hydroxyapatite coating could be demonstrated for the long-term soft tissue status.